What are the effects of single dose of L-theanine, and caffeine combination compared to placebo on selective attention in healthy acutely sleep-deprived young adults?

1. Study setting The study (behavioral and EEG tests) will be conducted in the Clinical Neurophysiology and Cognitive Neuroscience (CLINCON) laboratory at the Department of Physiology, Faculty of Medicine, University of Peradeniya. The CLINCON has the necessary testing equipment and other facilities.

2. The proposed study is not an RCT, rather a two-way crossover trial i.e., the same participant is given one treatment, and after a washout period, the other. The treatment order is counterbalanced in a Latin Square design (see Figure 2 on study design in the proposal). The treatment order is switched in each consecutive participant. e.g., first participant is given the active treatment first and the placebo second; and the second participant is given placebo first and the active treatment second and so on. L-theanine-caffeine combination and placebo will be administered on 2 separate days (one week apart) in a random counter-balanced order.

3. Intervention Active treatment: L-theanine-caffeine combination. Dose: 200mg L-theanine+160mg caffeine, powder incorporated into gelatin capsules Route: Orally Single dose, post-dose test will be carried out after 45 minutes ingestion of the active treatment Frequency- once

4. Control Gelatin capsule with 360mg of starch Route- Orally Single dose: post-dose test will be carried out after 45 minutes ingestion of the placebo. Frequency- once.

5. The proposed study is a double-blind study where both the participant and the test administrator will be blind to the treatment given. Participant will be blinded by giving all the treatments inside a capsule and the test administrator will be blinded by giving the treatment to the participant by a third person.

The subjects of the proposed study will have to strictly adhere to the following instructions. 1. Sleep at least 6 hours per night for 7 days before each testing session. 2. Avoid consumption of alcohol within 48 hours before the testing session. 3. Avoid any foods or beverages containing L-theanine or caffeine (tea, coffee, soft drinks, energy drinks of any food containing coffee) 24 hours before the testing session. 4. Washing hair, the day before or the morning of the day of testing and do not apply any hair ointments afterward (as preparation for EEG recordings). 5. Consume a light breakfast (equivalent to 4 slices of bread, 10 string hoppers, and 1 cup of rice) two hours before the test. on the day before testing, the participant will be allowed to continue their daily activities as usual and will be asked to have a 2-hour sleep after lunch. After this, the participant will be awake until the testing is finished on the following day.

On the day of testing, the subject can consume only a light breakfast (equivalent to 4 slices of bread, 10 string hoppers, and 1 cup of rice) for at least two hours before being tested. One member of the research team will maintain frequent contact with the participant to ensure that the participant is strictly following the instructions. On the day of testing, the participant will arrive at the testing place about 15 minutes before conducting the trial session. After arriving at the laboratory, the participant will be allowed to relax in the laboratory for 10 minutes. During this period, a test administrator will fill in the data sheet with relevant information to ensure that the participants had followed the instructions. Then setting up of EEG equipment will take place. This includes inserting scalp and face electrodes and connecting them to an EEG amplifier and data acquisition computer. This will take about 15 minutes. The traffic task-related oddball paradigm will be explained to the participant in their native language or any language with which they are most comfortable. Both speed and accuracy of performing the task will be emphasized to the participants to optimize outcomes. Thereafter the participants will do the pre-dose testing where they perform the visual oddball task with the EEG recording: this will constitute a 2-minute practice session followed by the actual task that lasted for about 15 min. EEG data will be recorded from the beginning of the practice session until the end of the task. After the pre-dose test, the subject will be given the treatment planned for that day. Afterward, the participant will remain seated for 45 minutes in the laboratory watching a non-stimulating documentary video of a genre they preferred (It is a routinely done procedure in these types of experiments to prevent them from getting bored). Afterward, the participant will be engaged in the post-dose test which will be identical to the Pre-dose task. After finishing the post-dose-test, the participant will be given the next appointment date and the preparation instructions; and will be allowed to leave the laboratory. Each visit will be similar except for the compound we give, which will be different on each visit.

The participants will be, sleep-deprived healthy young adults between the age of 20-30 years recruited from the community, both male and female.The participants in this study will be acutely sleep-deprived overnight before the day of the testing. The day before testing they will only have a post-lunch siesta for 2 hours. (Further details about sleep deprivation and the test preparation protocol are given in the attached protocol).

All individuals meeting any of the exclusion criteria at baseline will be excluded from study participation

1. Gross impairment of vision or hearing that would prevent the participants from performing neuropsychological tasks
2. Inability to read and follow written instructions
3. The participants who consume more than 5 cups of tea, coffee, or other caffeinated drinks per day.(Assessed by a qualified doctor in a detailed clinical interview conducted with the potential participants).
4. Who have alcohol dependence or abuse (Assessed by a qualified doctor in a detailed clinical interview conducted with the potential participants).
5. Who smoke or consume nicotine in any form. (Assessed by a qualified doctor in a detailed clinical interview conducted with the potential participants).
6. Who use recreational psychoactive drugs 7.Who have any longstanding illnesses like epilepsy, strokes, and any other neurological or psychiatric illnesses and have taken treatment for such illnesses
7. Who have a previous history of head trauma
8. Who have undergone a stressful or traumatic experience in the recent past.